Field of the Invention
The invention relates to a power converter, and more particularly, to a driver and a driving control method for a power converter.
Description of Related Art
FIG. 1 is a schematic view of a part of a conventional power converter. Referring to FIG. 1. In a conventional power converter 100, a driver 10 uses the diode 02 to allow a current to flow unidirectionally, so that an operation voltage VCC charges a capacitor Cb external to the driver 10.
Generally speaking, a forward bias Vf of the diode 02 is 0.7 volt. Therefore, the maximum voltage value of the capacitor Cb is the operation voltage Vcc minus the forward bias Vf (0.7 volt). That is, the capacitor Cb may only be charged up to “VCC−Vf” volts. The maximum voltage value is the upper limit of a driving voltage VB1. The driving voltage VB1 is mainly used as a power supply of a driving unit 04, and the driving unit 04 is used for driving the high side switch HS.
In addition, the operation voltage VCC may be a battery voltage. Therefore, when the battery voltage is full voltage, the voltage value of the operation voltage VCC is the maximum. The operation voltage VCC is reduced with the energy consumption of the battery. Moreover, the driving voltage VB1 equals the operation voltage VCC minus a fixed forward voltage Vf. Thus, due to the reduction in the voltage value of the operation voltage VCC, the voltage value of the driving voltage VB1 is reduced as well. In the worst case, when the voltage value of the driving voltage VB1 is reduced, the on-resistance of the high side switch HS increases and the on-condition of the high side switch HS becomes non-obvious, which also leads to a decrease in the power conversion efficiency of the power converter 100.